of turning were the all-important factors in the establishment of the habit.  At first it seemed as if the direction of turning was the chief determinant, and only by experimenting with colors under other conditions was I able to satisfy myself that the animals did notice differences in the appearance of their surroundings and act accordingly.  In Table IV. some results bearing on this point have been arranged.  To begin with, the habit of going to the left when the red was on the right at the entrance had been established; then, in order to see whether the colors influenced the choice, I reversed the conditions, placing the red on the left, that is, on the open-passage side.  The results as tabulated in the upper part of Table IV. show that the animals were very much confused by the reversal; at the entrance where there were several guiding factors besides the colors there were 50 per cent. of mistakes, while at the exit where there were fewer differences by which the animal could be directed it failed every time.  This work was not continued long enough to break up the old habit and replace it by a new one, because I wished to make use of the habit already formed for further experiments, and also because the animals remained so long in the labyrinth trying to find their way out that there was constant danger of losing them from too prolonged exposure to the dry air.

TABLE IV.

INFLUENCE OF CHANCES OF CONDITIONS.  FROG NO. 2.

Habit perfectly formed of going to Left (avoiding Red) at
entrance and to Right at exit.  Conditions now reversed.  Red on
Left.  Partition at Exit on Right.

Trials.          Entrance.              Exit.          Remarks. 
Right.      Wrong.      Right.      Wrong.
1- 5        3           2         0           5
6-10        2           3         0           5

Discontinued because animal remained so long in labyrinth that
there was danger of injuring it for further work.  This shows
that the habit once formed is hard to change.

Given 20 trials with conditions as at first in order to
establish habit again.

1-10        9           1         8            2
11-20       10           0         9            1

     Colors reversed, no other change.  To test influence of colors.

   1-10 6 4 10 0

  INFLUENCE OF DISTURBANCE WHEN ANIMAL IS ENTERING BOX.

          No Disturbance.  Animal Touched.

  To Red (Right).  To White (Left).  To Red.  To White.
        2 8 5 5

   This was after the tendency to go to the Left at the entrance
   had been established.